Logical fallacies
' Logical fallacies '''are errors in reasoning that undermine the logic of an argument because they lack support for a claim.http://owl.english.purdue.edu/owl/resource/659/03/ These can either take the form of illegitimate arguments or points that have no relevance to the current argument. Typically fallacies are used in lieu of solid arguments or may be used unknowingly. There are many types of logical fallacies in existence, too many to list in one page. Therefore, the most common will be listed below. Slippery Slope This argument is basically a long extension of the old geometry rule: if A=B and B=C, then A=C. It states that if one event were to occur, then another event would occur, which would lead to another, and another; usually until it reaches an unpopular occurance, like someone being murdered.http://www.csun.edu/~dgw61315/fallacies.html#Why%20learn%20fallacies The person arguing then states if we do not want said terrible event to happen, then the event in question can't happen. Here's an example: If we ban semi-automatic guns because they are dangerous, then the government will eventually ban all kitchen ware because they also present danger, therefore we should not have a semi-auto weapons ban. In the example, it is presented that a semi-automatic weapons ban equates a ban on kitchen ware, which is no where near the same thing. Appeal to Ignorance Such a fallacy is commited when something is assumed to be true because it hasn't been prove falsehttp://www.csun.edu/~dgw61315/fallacies.html#Argumentum%20ad%20ignorantiam. The burden of proof determines if this is fallacious or not. Only in the case of someone with the burden of proof is this fallacioushttp://www.csun.edu/~dgw61315/fallacies.html#Argumentum%20ad%20ignorantiam. An excellent example is the roles of the defendent and prosecution in court. The prosecution would be commiting appeal to ignorance if they were to asert "The defence has no alibi, therefore they must have commited the crime", but it would be perfectly okay if the defence said something like "Since the prosecution cannot prove my client commited these acts, he should be declared not guilty". This is because the burden of proof lies with the prosecution. ''Post hoc ergo propter hoc ''(after this, therefore because of this) This is the fallacy of assuming that just because one event happened before another event, that the first event caused the second http://www.csun.edu/~dgw61315/fallacies.html#Post%20hoc%20ergo%20propter%20hoc. Example: "Mary joined our class, a week later we all did poorly on a quiz. It must be her fault". In this instance, it proposes that because Mary joined the class, they all did bad. Without any further evidence for support, this claim becomes fallacious. Ad Hominem This is an attack on the person saying the idea or another thing not relevant to the argument, instead of the idea itselfhttp://www.csun.edu/~dgw61315/fallacies.html#Argumentum%20ad%20hominem. This can take many forms, but most commonly it is an attack on the source of the idea's backing. The example below is a fictional argument on morals, in regards to abortion, between two fictional characters; Steve the priest and Dan: Steve: "I believe that abortion is morally wrong." Dan: "Of course you would say that, you're a priest." Steve: "What about the arguments I gave to support my position?" Dan: "Those don't count. Like I said, you're a priest, so you have to say that abortion is wrong. Furthermore, you are just a slave to the Pope, so I can't believe what you say." The fact that Steve is a priest has little relevance in the argument with concern to the morals of abortion, thus making Dan's argument an Ad hominem. Begging the Question An argument "begs the question" when the premises, either stated or unstated, include the argument to be provedhttp://www.csun.edu/~dgw61315/fallacies.html#Petitio%20principii, as in the statement "stealing is illegal because it's against the law". This fallacy can be indentified with ease in some cases, such as in the pervious example, but more often it will occur in a more subtle form. It could like something more like this: "Opium induces sleep because it has a soporific quality". Such fallacies may not be immediately obvious in English because the English language has many synonyms; one way to beg the question is to make a statement first in concrete terms, then in abstract ones, or vice-versa. Another way this fallacy is used is by an unstated major premise. For example, if someone argues that we have to keep drugs illegal in order to prevent rampant drug abuse, the unstated major premise (which is found in the DNA of the argument itself, hence it's begging the question) is that legal drugs are abused less than illegal ones. Straw Man This is the attempt of "proving" an argument by over-simplifying the opponent's argument and attacking that instead of the actual argument http://web.cn.edu/kwheeler/fallacies_list.html. This often involves distorting arguments into something easier to fight and is usually a result of poor debate skills or the lack of valid counter arguments. An example would be two people arguing over if they should clean their fridge. ' ''' Person A: The fridge is getting messy. We should clean it. Person B: We just cleaned it a couple weeks ago. Person A: You just want to keep all the rotting and nasty food, which is ridiculous! The second statement person A made is a straw man argument due to the fact that they construed person B's reason not to clean into an obsession with spoiled food. Genetic Fallacy A conclusion that is based on the argument that the origin of an idea determines its worth or validityhttp://owl.english.purdue.edu/owl/resource/659/03/. Such an argument would be "That car can't possibly be good! It was made in Japan!". This fallacy is closely related to the Ad Hominem fallacy, because it can be perceived as an attack. Complex Question A complex question is a question that implies something to be true based on its structurehttp://www.csun.edu/~dgw61315/fallacies.html#Complex%20question. Such as the question " Have you stopped molesting children?". This would only be a fallacy if the fact that was presumed true was not established. This bald-faced version of complex questioning rarely appears in normal debatehttp://www.csun.edu/~dgw61315/fallacies.html#Complex%20question. Usually it appears in cross-examination or points of information where one person wants another to inadvertently admit to something they would normally not if asked directlyhttp://www.csun.edu/~dgw61315/fallacies.html#Complex%20question. Appeal to Authority This fallacy occurs when someone tries to add support to a claim by citing someone who agrees with their claim, even thought that person may have no knowledge on the subject being debatedhttp://www.csun.edu/~dgw61315/fallacies.html#Argumentum%20ad%20verecundiam. For instance, quoting Einsten on politics would be an appeal to authority fallacy. Now If you quoting him on physics, then this would no longer be a fallacyhttp://www.csun.edu/~dgw61315/fallacies.html#Argumentum%20ad%20verecundiam. References